New duvet covers can be expensive, but they are relatively easy to make yourself. All that's required to make one are a decent amount of fabric and a few hours of cutting and sewing. These instructions are for a twin size duvet cover but the same information can be applied to make a queen or king duvet cover as well -- you'll just need more fabric.
Measure the duvet that you would like to cover. Most fabrics don't come in wide enough widths for a duvet so you will most likely need to panel your fabric vertically to achieve the correct width. The cover in this post is for a twin size duvet which measures 64" x 86". Adding for seam allowance, the total dimensions of your cut panels, when stitched together, should be 65" x 90 1/2".
There are many different options for paneling fabric -- you can choose two different fabrics or create panels from the same fabric, it's up to you.
Since the shape of your duvet cover is a rectangle, there is no need to create a paper pattern to cut around. Simply, mark off the length and width you'd like to cut with a ruler and pencil.
For the wider panels, you can fold the fabric in half and cut through two layers at once. For the narrower panels, line up the edge of your ruler with the edge of the fabric and mark off the width you'd like. Keep making marks along the length of the fabric as this will ensure that you will get a straight line to cut on.
Stitch together your vertical panels using a French seam. A french seam encloses all the seam allowance so your fabric does not fray when put into the washing machine. It also makes the inside of your cover very clean looking.
To create a french seam, pin the WRONG sides of your fabric together and stitch using a 1/4" seam allowance. Once you've made your seam, trim off about 1/8" of the seam allowance width.
Iron your seam to one side, flip the fabric over (RIGHT sides will be facing each other now) and fold at the seam line. Pin the seam closed and stitch on your machine with 1/4" seam allowance. After sewing, iron your seams flat to relax the stitching.
You should now have two duvet pieces, a top and a bottom. The next step is to stitch the hem of each piece. Fold up a 1/2" hem and iron flat. Then fold up 2" and iron again. Pin up the fold and stitch with your machine about 1/8" in from the fold line.
Now it is time to add buttonholes to one side of your duvet hem. You can use 4 buttons for this duvet, evenly spaced in the center of your duvet. First, measure the buttons you purchased so you now how big to make the holes. These buttons are 9/16" so the button holes will be 3/4" long. Center the buttonholes between the bottom edge and the stitch line. Since the hem is 2" wide and the buttonholes are 3/4" long, each buttonhole will be placed at 5/8" above the bottom of the fabric.
Use the buttonhole function on your sewing machine to stitch your buttonholes. Once all of the buttonholes are sewn, you need to use a seam ripper to cut them open. Start at the bottom of the buttonhole (above the thread), stick your seam ripper in and slide it to the top of the buttonhole.
Once your buttonholes are in, you can stitch the two sides of your duvet together. You can also use the French seam technique but if your fabric is heavy, it might get too thick at the corners. In that case, pin the right sides of your fabric together and stitch around the cover, starting from the left side of your buttonholes and ending on the right side. Then you can clean finish your seam allowance by using a zigzag stitch along the edge.
Flip your cover right side out and lie flat. Use your buttonholes to mark the correct placement of your buttons and stitch your buttons on. Place your duvet into your new cover and you're done!
If your duvet has loops of twill tape at the corners, you can stitch twill tape ties into the corners of your duvet to hold the duvet in place.
There are many different options to close your duvet cover besides buttonholes. You can use snaps, twill tape ties, even velcro!
The same instructions apply to create a queen or king size duvet as well, just make sure to measure your duvet to adjust for the amount of fabric needed.